This invention relates to a method of scrapping a furnace bottom section of a blast furnace, more particularly, to a method of scrapping a furnace bottom section of a blast furnace which can convey solidified residual iron left in the furnace bottom section after performing a blowing-down for revamping the blast furnace out of the furnace.
When operating a blast furnace for a long time, the brick lining is significantly corroded. When removing the corrosion, in an upper portion of the blast furnace, a crack is generated in the shell provided on the outer periphery as a pressure container and gas or the like is injected out, and in a lower portion of the blast furnace, carbon bricks in the furnace bottom section are corroded and dissolved material melts down the shell and flows out. In such a case, a water vapor explosion may be generated by stave cooling water or shell cooling water. Accordingly, the blast furnace is blown out and an inner portion thereof is revamped once every ten or so years.
At the time of revamping the blast furnace, an opening portion is formed by partly breaking the shell in the furnace bottom section of the blast furnace and the brick lining with construction machinery such as a back hoe, a shovel or the like, and the construction machinery is introduced into the inner portion of the furnace bottom section. Then, coke left in the furnace bottom section is removed from the furnace by the construction machinery. Thereafter, it is necessary that an operator enters the furnace and crushes solidified residual iron left in a lower portion thereof, the solidified residual iron mainly containing pig iron with which slag or coke is mixed, by employing a rock drill or blasting, to convey solidified residual iron out of the furnace.
The solidified residual iron is firmly integrated and hard to be decomposed, which is different from a collapsible solidified material, and is removed by blasting. It has been necessary to form a multiplicity of bores in the solidified residual iron by a boring drill or an oxygen lance prior to the blast and charge dynamite therein, prior to the blast. In this boring, blasting and dividing method mentioned above, since a long time is required, a long period is required for the construction, so that the blasting operation avoids other scrapping operations. Further, since the crushed materials are dispersed at the time of explosion and a significant danger and loud sound are generated, the operation performed in the periphery of the blast furnace is necessarily interrupted at the time of blasting.
In this case, since the period of the construction for revamping the blast furnace is required to be reduced as much as possible, the scrapping operation is started before the brick lining and the solidified residual iron within the furnace body are cooled to room temperature. Accordingly, the environment of the operation is a bad environment in which the temperature is high and a lot of dust is generated. Further, since the brick lining and the solidified residual iron are hard and heavy, it is necessary to divide them into small components to convey them from the opening portion provided in the furnace bottom section. For the reasons mentioned above, the time required for the conventional scrapping operation has become very long and as a result, the operation is costly.
Further, an outrigger crane placed in a supporting column for maintenance may be used. In this case, the shell in the furnace bottom section of the blast furnace has been cut to form short strips having a weight of 5 to 50 tons and has been taken out by the outrigger crane, and the solidified residual iron is removed from the furnace through the opening portion provided in the furnace bottom section of the blast furnace.
Further, as another method, a method of revamping an inner portion of a blast furnace is disclosed in Japanese Unexamined Patent Publication Nos. 10-96005 and 7-197112. A method of scrapping a furnace bottom section of a blast furnace described in Japanese Patent Unexamined Publication No. 10-96005 is structured to cut a lower portion of the furnace, suspend and fix a furnace body of the blast furnace by a supporting column, thereafter scrap a shell in the lower portion of the furnace, horizontally cut solidified residual iron within the blast furnace with a wire saw and integrally take out the solidified residual iron. On the contrary, a method of conveying solidified residual iron in a furnace bottom section of a blast furnace out of the furnace described in Japanese Patent Unexamined Publication No. 7-197112 is structured to place a jack between a solidified residual iron in the periphery within the blast furnace and a furnace bottom section to lift up in a vertical direction, thereafter insert an object for reducing a coefficient of friction such as a cylinder or the like and take out the solidified residual iron.
However, the conventional methods of scrapping the furnace bottom section of the blast furnace have the following problems.
(1) In the method using the outrigger crane, since the solidified residual iron within the blast furnace is a large-size solidified residual iron having a weight of about 500 ton, while the suspending capacity of the outrigger crane is about 70 to 200 ton, it is necessary to divide the solidified residual iron into small pieces.
(2) In the method described in Japanese Patent Unexamined Publication No. 10-96005, a long time is required for the cutting operation of the brick and a lot of labor is required to remove the solidified residual iron.
(3) In the method described in Japanese Patent Unexamined Publication No. 7-197112, the size of the conveyed-out solidified residual iron is limited even when the coefficient of friction of the solidified residual iron and the furnace bottom section brick is reduced by using a cylinder or the like.
Further, since the supporting column for supporting the furnace body is provided in the outer periphery of the blast furnace, it is necessary to perform the operation not to interfere with the supporting column at the time of conveying the solidified residual iron out of the furnace whichever method is employed.
In accordance with the invention, there is provided a method of scrapping a furnace bottom section of a blast furnace comprising the steps of:
horizontally cutting a furnace body of the blast furnace after being blown out at a position higher than solidified residual iron left in the furnace bottom section;
suspending an upper frame body above the cutting position by employing vertically moving means placed in a supporting column;
taking out at least a part of a shell and a brick lining in a lower furnace body below the cutting position all around the periphery; and
thereafter conveying the solidified residual iron out of the furnace,
wherein the upper furnace body and the solidified residual iron are integrally connected by using a suspending device before conveying the solidified residual iron out of the furnace, and the upper furnace body and the solidified residual iron are vertically moved by using the vertical moving means.
In accordance with the invention mentioned above, it is preferable to make the structure such that a plurality of cavities are provided along a peripheral portion of the solidified residual iron and at a plurality of portions between the solidified residual iron and the furnace bottom brick before conveying the solidified residual iron out of the furnace, the solidified residual iron is jacked up by a lifting-up jack arranged in the cavity to form a gap between the solidified residual iron and the furnace bottom brick, a solidified residual iron suspending band (herein after referred to as xe2x80x9csuspending bandxe2x80x9d) is inserted into the gap. Thereafter, the upper furnace body suspended in the supporting column is lowered by using the vertical moving means so that the suspending band is connected to the suspending device fixed to a lower portion of the upper furnace body. Next, the upper furnace body is suspended together with the solidified residual iron by using the vertical moving means so that an operating space is formed between the solidified residual iron and the furnace bottom brick or a bottom plate of the blast furnace and a horizontally moving table is moved on the furnace bottom brick or the bottom plate of the blast furnace. Thereafter, the upper furnace body and the solidified residual iron are lowered by using the vertical moving means to be mounted on the horizontal moving table. Next, the suspending device fixed to the lower portion of the upper furnace body is separated. Thereafter, the upper furnace body is evacuated upwardly by using the vertical moving apparatus, and the horizontal moving table mounting the solidified residual iron thereon is moved from the inner portion of the furnace to the outer portion of the furnace.
Further, it is preferable to make the structure such that the suspending device is fixed to a tuyere of the upper furnace body.
Further, it is preferable to make the structure such that a surface layer portion of the furnace bottom brick is flattened under the operating space formed between the solidified residual iron and the furnace bottom brick, or the furnace bottom brick is removed. Thereafter, a furnace inner rail is placed on the furnace bottom brick or the bottom plate of the blast furnace, and the horizontal moving table is moved on the furnace inner rail.
Further, it is preferable to make the structure such that a surface layer portion of the furnace bottom brick is flattened under the operating space formed between the solidified residual iron and the furnace bottom brick, or the furnace bottom brick is removed. Thereafter, the horizontal moving table having a solidified residual iron receiving table detachably arranged in a plurality of through holes is moved onto the furnace brick or the bottom plate of the blast furnace, the upper furnace body and the solidified residual iron are descended by using the vertical moving means to be mounted on the solidified residual iron receiving table, a lower end surface of the solidified residual iron receiving table is grounded on the furnace bottom brick or the bottom plate of the blast furnace due to a deadweight of the solidified residual iron so that a construction space is formed between the horizontal moving table and the furnace bottom brick or the bottom plate of the blast furnace, and the furnace inner rail is placed on the furnace bottom brick or the bottom plate of the blast furnace under the construction space. Thereafter, the upper furnace body and the solidified residual iron are suspended by using the vertical moving means so that solidified residual iron receiving table is taken out from the horizontal moving table, and the upper furnace body and the solidified residual iron are lowered by using the vertical moving means to be mounted on the horizontal moving table. Next, the suspending device fixed to the lower end portion of the upper furnace body is separated. Thereafter, the upper furnace body is evacuated upwardly by using the vertical moving apparatus, and the horizontal moving table mounting the solidified residual iron thereon is moved to the outer portion of the furnace from the inner portion of the furnace.
Further, it is preferable to make the structure such that a receiving shelf is provided in a through hole provided in the horizontal moving table. The solidified residual iron receiving table is supported with respect to the receiving shelf via a plurality of springs by a bracket provided on an upper side surface thereof. A lower end surface of the solidified residual iron receiving table is moved apart from the furnace bottom brick or the bottom plate of the blast furnace due to elastic force of the spring when the horizontal moving table is moved onto the furnace bottom brick or the bottom plate of the blast furnace. The spring is compressed via the bracket when the solidified residual iron is mounted on the solidified residual iron receiving table so that the lower end surface of the solidified residual iron receiving table is grounded on the furnace bottom brick or the bottom plate of the blast furnace, and the construction space is formed between the horizontal moving table and the furnace bottom brick or the bottom plate of the blast furnace.
Further, it is preferable to make the structure such that the horizontal moving table arranged on the furnace inner rail is moved via a roller or a slide shoe arranged in a lower portion of the horizontally moving table.
Further, it is preferable to make the structure such that the slide shoe is arranged within a groove formed in the furnace inner rail, a friction coefficient reducing member is interposed between the slide shoe and the groove formed in the furnace inner rail, and the horizontal moving table is moved due to sliding motion along the groove formed in the furnace inner rail of the slide shoe.
Further, it is preferable to make the structure such that the friction coefficient reducing member is made of Teflon(copyright) and/or stainless steel.
Further, it is preferable to make the structure such that the shape of the suspending band is formed in a Y shape.
Further, it is preferable to make the structure such that the shape of the suspending band is formed in a web shape, and the solidified residual iron is suspended by crossing two web-like suspending bands to form an X shape.
Further, it is preferable to make the structure such that the solidified residual iron is separated to be suspended together with the upper furnace body by using the vertical moving means.
Further, it is preferable to make the structure such that the solidified residual iron mounted on the horizontal moving table is separated.
Further, it is preferable to make the structure such that a beam is arranged within the upper furnace body, the beam and the solidified residual iron are connected by using the suspending member, and the solidified residual iron is suspended by using the suspending member and the suspending band.